Working out a BEC project, several questions so far.
Discussion
Hi there
I joined here via Google, searching about info on chassis setups, and various choices of Bike engines put into cars or kitcars.
I'll go straight to the point :
My Plan is to convert a Reliant Robin type car to Bike power.
Let's be clear, I'm not interested in biased views based on Clarkson and the Stigs inability to drive them in the Top Gear feature they did, and to the fact that they have bad handling characteristics.
That, is a given fact, in standard form, and, to be honest, give me a car with 4 wheels, and I'll easily be able to roll it if I drive it like a monkey.
I've owned all sorts of weird and powerful cars, but these are quite special, and not so ridiculous in stock shape actually, they are perfectly capable of keeping up with modern traffic today.
This was my last Reliant based 3 wheeler : A Bond Bug fitted with a 1000 cc R1 engine (4XV)
This was not built by me, but by a very talented guy, the car was truly a piece of art, quality was flawless.
Specs :
1974 Bond Bug
Weight : 395 kg
Engine : 1000 cc R1 4XV, around 150 HP give or take
Diff : 2,78:1 (Reliants own long eco ratio)
The Bond Bug chassis (pictured below), unlike the Reliant Robin/Rialto etc, has a very good rear suspension setup, no leaf springs and measly shock absorbers, it came standard with a 4 link rear axle and coilovers. Bags more cornering than a Reliant. No, really, I'm serious, haha. This car had Spax adjustables that were tuned in really nicely.
A few minutes of film of the car in action :
https://www.youtube.com/watch?v=ihFhSrS66Cg
Top speed around 130 mph, the original R1 Speedo was equipped with a Speedo healer that was calibrated with a GPS, so that what pretty accurate... :^D
Having sold that, and, majorly regretting it, I've decided to have a decent go at building my own.
But, wish to improve on the original concept I owned before.
Flaws of the Bond Bug that need addressing :
- the diff/Axle assembly :
The R1 is said to have 150 HP @ 10500 rpm or so, and 72.7 lb·ft @ 8250 rpm. that's what Yamaha claims, and thats not WHP, I seriously must have lost a few over the prop, diff and extra wheel to move...
But the main problem is, that to make use of the 150 whatever HP, (4 times original engine output, and at much higher revs) I'd be seriously abusing the diff, squeezing the revs out of it to hit the powerband.
It clearly was the fuse of the car, and hence I never really used that much of the HP available...
- Engine :
It was too revvy, output and torque are placed too high for it to be that comfortable to drive. It surely was bags of fun, but a better engine choice can be made. Main reason why he chose the R1, is because it is so compact, that he hardly had to mod the body to get it to fit, even the OE engine cover was useable...
- Suspension :
Frankly it was good, and as good as it could get on the OE setup. Not comfortable, very hard, wide cornering above 65 mph was totally doable, but there has to be room for improvement.
Here are the project ideas so far :
- Diff/Axle assembly/chassis :
In the 80s, an american company based in California went on a venture to produce a Reliant Rialto with hybrid or electric engines. They fitted an extra wide rear axle for improved cornering :
Now, a rear end this wide is ridiculous, but it is without a doubt a manner of improving cornering.
The problem with a RWD 3 wheeler like a Reliant, is that when in spirited driving, the rear end wants to kick out in corners, so the car will want to slide... add the factor that there is no front wheel to lean on, and obviously the car lifts the opposite rear wheel...
Add to the equation that it is a live narrow rear axle, and the ride height is quite massively high, and that's not going to help.
My first idea of improvement is to lower the ride height. that's "easy" enough.
Second idea, (related to the diff choice, also) is to adapt a rear subframe from an early BMW 2002, just like this :
This has about a 4 inches wider track than the Reliant, which can be aided by rim offset also if wider needs be, but I'm thinking, based on my experience with the 4 link "sports" setup of the car I had, that I might not need that much wider track ? Adding this IRS setup to the mix must surely help also, rather than the stiff tube axle that doesn't allow flexibility ?
Any ideas on that, theoretically (not 3 wheeler based experience, of course) ?
Using an older BMW rear subframe, allows me to adapt a BMW diff, another big point of the rear end issues. Reliants 2,78:1 diff ratio was superbly long and plug and play, but too weak to make the most of the engine.
the 325 TDS E36 was supplied with a 2,56 diff, that will reduce revs at a same given speed, and improve top end if needed... I haven't found anything longer than that, and based on my experience with the Bond Bug (7000 rpm @ 80 MPH...) I sure could do with a bit of a quieter running machine...
And a BMW diff can no doubt handle 200hp and 13 kgm of torque all day, no ?
- Engine :
Torque, I want torque, obviously... But how much ? 1000cc Sportsbikes have improved in both HP and torque over the years, but it's always at High rpms, mainly...
FWIW, the car will hopefully weigh in UNDER 400kg.
Original engine :
Max Power
40 hp @ 5500 rpm
Max Torque
6,3 kg-m @ 3500 rpm
2 options have sprung to mind :
First Option (sane) :
955i Triumph triple :
Max Power
120 hp @ 9100 rpm
Max Torque
10.2 kg-m @ 5100 rpm
Thats 3 times the power, at only 3500 rpm higher, and 50% more torque only 1500 rpm higher.
I'm thinking that would be Lots of fun, very useable due to low RPM outputs, but I'm also wondering if it's not too little of a result for such work ?
Second option (less sane) :
ZZR 1400 :
Max Power
187 hp @ 9500 rpm
Max Torque
13.87 kg-m @ 7500 rpm
That's 5 times the OE power, at around the same RPM as the Triumph, and more than twice the torque at twice the RPM than the OE engine... That is going towards the revvy 1000s that I don't really want, but the supply is awesome. My concerns are getting that power down to the road...
Any info on dimensions of these engines ? And reliable OE Dyno charts ?
This car, if set up properly, would be quite excellent in corners if :
a - it has the chassis to "slide" without grabbing (and therefore rolling) in corners (lower ride, IRS, wider track, "bad" quality not too wide tyres)
b - it has the BHP at the right RPM to drift it in and out of said corners.
and any time lost in corners compared to a 4 wheeler would be caught up in the straights anyway :^)
Finally, this will be a road car/occasional track day car. And a proper build, too, not a Chavmobile built to crappy standards, and usually not finished before being ebayed.
I've almost written a book, congrats to those who've trawled through all my ranting crap.
Any serious advice on my chassis setup ideas more than welcome.
I joined here via Google, searching about info on chassis setups, and various choices of Bike engines put into cars or kitcars.
I'll go straight to the point :
My Plan is to convert a Reliant Robin type car to Bike power.
Let's be clear, I'm not interested in biased views based on Clarkson and the Stigs inability to drive them in the Top Gear feature they did, and to the fact that they have bad handling characteristics.
That, is a given fact, in standard form, and, to be honest, give me a car with 4 wheels, and I'll easily be able to roll it if I drive it like a monkey.
I've owned all sorts of weird and powerful cars, but these are quite special, and not so ridiculous in stock shape actually, they are perfectly capable of keeping up with modern traffic today.
This was my last Reliant based 3 wheeler : A Bond Bug fitted with a 1000 cc R1 engine (4XV)
This was not built by me, but by a very talented guy, the car was truly a piece of art, quality was flawless.
Specs :
1974 Bond Bug
Weight : 395 kg
Engine : 1000 cc R1 4XV, around 150 HP give or take
Diff : 2,78:1 (Reliants own long eco ratio)
The Bond Bug chassis (pictured below), unlike the Reliant Robin/Rialto etc, has a very good rear suspension setup, no leaf springs and measly shock absorbers, it came standard with a 4 link rear axle and coilovers. Bags more cornering than a Reliant. No, really, I'm serious, haha. This car had Spax adjustables that were tuned in really nicely.
A few minutes of film of the car in action :
https://www.youtube.com/watch?v=ihFhSrS66Cg
Top speed around 130 mph, the original R1 Speedo was equipped with a Speedo healer that was calibrated with a GPS, so that what pretty accurate... :^D
Having sold that, and, majorly regretting it, I've decided to have a decent go at building my own.
But, wish to improve on the original concept I owned before.
Flaws of the Bond Bug that need addressing :
- the diff/Axle assembly :
The R1 is said to have 150 HP @ 10500 rpm or so, and 72.7 lb·ft @ 8250 rpm. that's what Yamaha claims, and thats not WHP, I seriously must have lost a few over the prop, diff and extra wheel to move...
But the main problem is, that to make use of the 150 whatever HP, (4 times original engine output, and at much higher revs) I'd be seriously abusing the diff, squeezing the revs out of it to hit the powerband.
It clearly was the fuse of the car, and hence I never really used that much of the HP available...
- Engine :
It was too revvy, output and torque are placed too high for it to be that comfortable to drive. It surely was bags of fun, but a better engine choice can be made. Main reason why he chose the R1, is because it is so compact, that he hardly had to mod the body to get it to fit, even the OE engine cover was useable...
- Suspension :
Frankly it was good, and as good as it could get on the OE setup. Not comfortable, very hard, wide cornering above 65 mph was totally doable, but there has to be room for improvement.
Here are the project ideas so far :
- Diff/Axle assembly/chassis :
In the 80s, an american company based in California went on a venture to produce a Reliant Rialto with hybrid or electric engines. They fitted an extra wide rear axle for improved cornering :
Now, a rear end this wide is ridiculous, but it is without a doubt a manner of improving cornering.
The problem with a RWD 3 wheeler like a Reliant, is that when in spirited driving, the rear end wants to kick out in corners, so the car will want to slide... add the factor that there is no front wheel to lean on, and obviously the car lifts the opposite rear wheel...
Add to the equation that it is a live narrow rear axle, and the ride height is quite massively high, and that's not going to help.
My first idea of improvement is to lower the ride height. that's "easy" enough.
Second idea, (related to the diff choice, also) is to adapt a rear subframe from an early BMW 2002, just like this :
This has about a 4 inches wider track than the Reliant, which can be aided by rim offset also if wider needs be, but I'm thinking, based on my experience with the 4 link "sports" setup of the car I had, that I might not need that much wider track ? Adding this IRS setup to the mix must surely help also, rather than the stiff tube axle that doesn't allow flexibility ?
Any ideas on that, theoretically (not 3 wheeler based experience, of course) ?
Using an older BMW rear subframe, allows me to adapt a BMW diff, another big point of the rear end issues. Reliants 2,78:1 diff ratio was superbly long and plug and play, but too weak to make the most of the engine.
the 325 TDS E36 was supplied with a 2,56 diff, that will reduce revs at a same given speed, and improve top end if needed... I haven't found anything longer than that, and based on my experience with the Bond Bug (7000 rpm @ 80 MPH...) I sure could do with a bit of a quieter running machine...
And a BMW diff can no doubt handle 200hp and 13 kgm of torque all day, no ?
- Engine :
Torque, I want torque, obviously... But how much ? 1000cc Sportsbikes have improved in both HP and torque over the years, but it's always at High rpms, mainly...
FWIW, the car will hopefully weigh in UNDER 400kg.
Original engine :
Max Power
40 hp @ 5500 rpm
Max Torque
6,3 kg-m @ 3500 rpm
2 options have sprung to mind :
First Option (sane) :
955i Triumph triple :
Max Power
120 hp @ 9100 rpm
Max Torque
10.2 kg-m @ 5100 rpm
Thats 3 times the power, at only 3500 rpm higher, and 50% more torque only 1500 rpm higher.
I'm thinking that would be Lots of fun, very useable due to low RPM outputs, but I'm also wondering if it's not too little of a result for such work ?
Second option (less sane) :
ZZR 1400 :
Max Power
187 hp @ 9500 rpm
Max Torque
13.87 kg-m @ 7500 rpm
That's 5 times the OE power, at around the same RPM as the Triumph, and more than twice the torque at twice the RPM than the OE engine... That is going towards the revvy 1000s that I don't really want, but the supply is awesome. My concerns are getting that power down to the road...
Any info on dimensions of these engines ? And reliable OE Dyno charts ?
This car, if set up properly, would be quite excellent in corners if :
a - it has the chassis to "slide" without grabbing (and therefore rolling) in corners (lower ride, IRS, wider track, "bad" quality not too wide tyres)
b - it has the BHP at the right RPM to drift it in and out of said corners.
and any time lost in corners compared to a 4 wheeler would be caught up in the straights anyway :^)
Finally, this will be a road car/occasional track day car. And a proper build, too, not a Chavmobile built to crappy standards, and usually not finished before being ebayed.
I've almost written a book, congrats to those who've trawled through all my ranting crap.
Any serious advice on my chassis setup ideas more than welcome.
Edited by Reliant on Wednesday 5th April 18:04
Indeed, it's a bit of just because i can.
But honestly they're fun cars in stock form, and with a bike engine even more so. Not to mention the look on peoples faces. I actually outran a mk5 golf gti on a moderately curvy road in my r1 bug, and judging by the view in the mirror the guy was clearly trying :^D
Reliant Kitten 4 wheeler would indeed have been a better start (double wishbone coilover front axle as standard equipment), but i prefer the tripods and like the challenge of making the illogical a bit more logical
But honestly they're fun cars in stock form, and with a bike engine even more so. Not to mention the look on peoples faces. I actually outran a mk5 golf gti on a moderately curvy road in my r1 bug, and judging by the view in the mirror the guy was clearly trying :^D
Reliant Kitten 4 wheeler would indeed have been a better start (double wishbone coilover front axle as standard equipment), but i prefer the tripods and like the challenge of making the illogical a bit more logical
Edited by Reliant on Wednesday 22 April 22:54
Thanks for your input Chris. I do believe it will change the driving experience substantially, although in the case of the Reliant it will add a bit of weight overall.
More research is being done before anything gets started yet but i'm on the right track i think.
After all, Nissan did very well at the 24hrs with theirs, so I'm sure I'll be OK with my minor attempt
More research is being done before anything gets started yet but i'm on the right track i think.
After all, Nissan did very well at the 24hrs with theirs, so I'm sure I'll be OK with my minor attempt
Edited by Reliant on Wednesday 22 April 22:55
rhinochopig said:
@ Dave Brookes :
I'm not planning on skimping on the job, but I'd rather not go too overboard on the final budget. Of course, the car finished and done will probably still be cheaper than just a set of cams for a Testarossa engine
, but I reckon the home grafted IRS will be good enough for the project (and yes indeed, the rear diff... haha)@ Chris :
Indeed more weight on the back should also mean some gain in traction if I'm not mistaken ?
There's a good video on youtube about the Nissan Deltawing, Chris Harris has a chat with the guy who designed the thing, he explains chassis theory, of course hardly any is relevant but some of it sounds OK as far as this 3 wheeler is concerned.
There's a guy who built a 350HP hayabusa engined Bond Bug, Z-Cars took care of the chassis, lowered height, with IRS and a Sierra diff. Never seen it perform on the road, but the builder who I met said it was nicely setup for cornering. As for performance : 0-60 in 3 sec, top speed 120 or so, 1/4m in 10,4, and 0-120 in 8 sec
My plan was to adapt the e36 diff to fit the 02 rear subframe ? I need the rear arms setup, then i jyst need to support the e36 diff and work out drive shafts
I do need the highest diff ratio possible in order to keep revs down in a comfortable region. Hence the 2,56:1 TDS diff
No idea what is available on mx5, i'll go look into that, but i'm guessing it's a bulky/heavy unit ? I do need to keep weight down
Thanks
I do need the highest diff ratio possible in order to keep revs down in a comfortable region. Hence the 2,56:1 TDS diff
No idea what is available on mx5, i'll go look into that, but i'm guessing it's a bulky/heavy unit ? I do need to keep weight down
Thanks
Edited by Reliant on Thursday 4th June 14:44
Hey
I'm digging this up, the project is slowly evolving.
Turns out I wasn't able to find a good Mk1 Reliant Robin saloon before I managed to cross paths with an unfinished resto project of a Bond Bug.
So, seeing that it is sold without a motor, I'm happy to announce that it's going to be the racier sportier looking Bug being converted to bike power.
I've been looking at diffs available, i was thinking of using the BMW 2,56:1 easily available.
Trawling through ebay listings on german ebay, in the hope of finding dimension infos, i actually found out that more recent diesel beemers were supplied with :
- 2,47
And even
- 2,35
Damn thats tall !
So, i was wondering what BEC that are diff driven usually use in terms of diff gearing ?
Seeing that bikes have a gearbox output usually around 1,5 (I read somewhere that the ZZR1400, which i'll probably be using is 1,556:1)
That means a real final drive of 3,65:1 if i'm not mistaken, once bolted to the tallest BMW diff ?
Thanks for your insight
I'm digging this up, the project is slowly evolving.
Turns out I wasn't able to find a good Mk1 Reliant Robin saloon before I managed to cross paths with an unfinished resto project of a Bond Bug.
So, seeing that it is sold without a motor, I'm happy to announce that it's going to be the racier sportier looking Bug being converted to bike power.
I've been looking at diffs available, i was thinking of using the BMW 2,56:1 easily available.
Trawling through ebay listings on german ebay, in the hope of finding dimension infos, i actually found out that more recent diesel beemers were supplied with :
- 2,47
And even
- 2,35
Damn thats tall !
So, i was wondering what BEC that are diff driven usually use in terms of diff gearing ?
Seeing that bikes have a gearbox output usually around 1,5 (I read somewhere that the ZZR1400, which i'll probably be using is 1,556:1)
That means a real final drive of 3,65:1 if i'm not mistaken, once bolted to the tallest BMW diff ?
Thanks for your insight
Edited by Reliant on Friday 5th February 20:12
Ok.
is my theory correct as far as multiplying the bike gearbox output ratio by the diff ratio to get the final ratio ?
I had a 2,78 on my first bond bug, so times the 1,5 approx ratio of the bug, that meant 4,17:1 ?
It was fitted with 175/65/13, not really possible to put bigger on it.
I seem to remember it was hitting 7000 rpm at 80 mph.....
I agree that i won't be driving at 120 mph all the time, and a bit of a smoother ride would be good. 200hp and so much torque is heaps more than enough to pull the thing.
Weight will probably be around 400-420 kilos, what with extra bracing and heavier rear axle/end
is my theory correct as far as multiplying the bike gearbox output ratio by the diff ratio to get the final ratio ?
I had a 2,78 on my first bond bug, so times the 1,5 approx ratio of the bug, that meant 4,17:1 ?
It was fitted with 175/65/13, not really possible to put bigger on it.
I seem to remember it was hitting 7000 rpm at 80 mph.....
I agree that i won't be driving at 120 mph all the time, and a bit of a smoother ride would be good. 200hp and so much torque is heaps more than enough to pull the thing.
Weight will probably be around 400-420 kilos, what with extra bracing and heavier rear axle/end
Edited by Reliant on Friday 5th February 21:05
Russ-l1hze said:
We use the ZZR1400 in the Furore, all up weight of around 565kg (plus driver & passenger), running 245/45/17 tyres, we run 3.28:1, this gives 70mph at 4750rpm or thereabouts, which is pretty relaxed for a bike engine.
If you are running similar weight & tyre size then anything around 3.1 - 3.4 should be fine, if your tyre diameter is smaller (which I suspect it will be) then you'll probably want to go a bit lower, it's worth sacrificing a fraction of acceleration for a more relaxed cruise in my opinion
In theory your tyres are 10cm taller in diameter than those i had on my R1 Bug.If you are running similar weight & tyre size then anything around 3.1 - 3.4 should be fine, if your tyre diameter is smaller (which I suspect it will be) then you'll probably want to go a bit lower, it's worth sacrificing a fraction of acceleration for a more relaxed cruise in my opinion
Motorway speed in France is 80mph, as i said, with the 2,78 rear end, the R1 was doing 7000 rpm pulling a 400 kilo car...
I guess that is due to :
- less HP
- less torque (much less)
To pull the extra weight and work against the extra drag, to achieve a similar speed.
If i understand correctly, the superior engine characteristics of the ZZR means that a shorter diff ratio could be used ?
This car will be built for the road, and occasional track day, i would really appreciate the kind of speed/rpm ratio you have on your car, it was earbleeding hell crusing on the motorway with my R1...
Edited by Reliant on Saturday 6th February 09:17
Toltec said:
Yeah, weird but fun nonetheless.Indeed the deltawing is a great technical feat, there is some info out therr about it, but i think resdesigning a complete frond end is a bit above my capacities
Nice ride. Was it converted later on to bike power ?
What RPM are you reaching at the 125 mph mark ?
Sounds like I do need to be above 3:1 with the small tyres i'll be having to use. Obviously i won't be reaching max speed but with a ZZR1400 there should be enough torque to get good acceleration and keep revs down a bit, even with a high ratio diff
My R1 bug with 2,78:1 I got to 120mph (GPS calibrated speedo healer) and i was around 10000 rpm
What RPM are you reaching at the 125 mph mark ?
Sounds like I do need to be above 3:1 with the small tyres i'll be having to use. Obviously i won't be reaching max speed but with a ZZR1400 there should be enough torque to get good acceleration and keep revs down a bit, even with a high ratio diff
My R1 bug with 2,78:1 I got to 120mph (GPS calibrated speedo healer) and i was around 10000 rpm
Edited by Reliant on Tuesday 9th February 16:56
Hi
Thank you both for your input.
I may have figures badly recorded in my head, maybe indeed it was lower @ 80mph
But the diff indeed was 2.78:1, the guy kept the Bond Bug specific half drives of the axle, and slipped them onto a diff casing from a 1984 Reliant Rialto "eco", that was fitted with a low torque tuned engine to pull the Reliant made 2,78:1 diff specific to this version.
I have no doubt the zzr1400 will pull a tall geared diff, seeing how the R1 performed. The compromise in my case, is to find the right balance between comfortable engine noise and acceleration.
With a higher diff, theoretical top speed will be higher, but it's not much of a concern if I can't reach it as long as acceleration is still in the near lethal zone
thanks for the excel sheet, i will look into it. And nope that wasn't my bug on the trailer.
Thank you both for your input.
I may have figures badly recorded in my head, maybe indeed it was lower @ 80mph
But the diff indeed was 2.78:1, the guy kept the Bond Bug specific half drives of the axle, and slipped them onto a diff casing from a 1984 Reliant Rialto "eco", that was fitted with a low torque tuned engine to pull the Reliant made 2,78:1 diff specific to this version.
I have no doubt the zzr1400 will pull a tall geared diff, seeing how the R1 performed. The compromise in my case, is to find the right balance between comfortable engine noise and acceleration.
With a higher diff, theoretical top speed will be higher, but it's not much of a concern if I can't reach it as long as acceleration is still in the near lethal zone
thanks for the excel sheet, i will look into it. And nope that wasn't my bug on the trailer.
Edited by Reliant on Friday 19th February 21:14
I remember seeing a photo in progress of a bond bug with a boxer BMW engine, but no evidence of it finished. Was some years ago now.
Checking the specs, the K1100 is basically a 955i Tiger engine as far as output/torque/rpm goes.
But never having seen one, not sure how the flat 4 sits as far as engine bay clearance goes
I've seen a ZX12R with less than 5000 on the clock (full new engine exchange at the dealers, invoices etc to prove it). Price is good, so looks like i'll be using a smaller lump (although the torque/rpm is the same as the first ZZR1400).
I get what you mean by more subtle with a GT bike, but I would rather have a sportier engine seeing that I'll be massaging the chassis setup to make more out of the bike engine than my previous R1 bug
Checking the specs, the K1100 is basically a 955i Tiger engine as far as output/torque/rpm goes.
But never having seen one, not sure how the flat 4 sits as far as engine bay clearance goes
I've seen a ZX12R with less than 5000 on the clock (full new engine exchange at the dealers, invoices etc to prove it). Price is good, so looks like i'll be using a smaller lump (although the torque/rpm is the same as the first ZZR1400).
I get what you mean by more subtle with a GT bike, but I would rather have a sportier engine seeing that I'll be massaging the chassis setup to make more out of the bike engine than my previous R1 bug
Edited by Reliant on Friday 25th March 21:54
Edited by Reliant on Friday 25th March 22:02
Ah indeed, you must be talking about this one :
http://aasilencers.co.uk/blog/tag/reliant-robin
?
I found that car via a google search some time ago, description sounds promising in the blog but not much visual details of any setup.
Need to see if i can reach him directly. His front end setup sounds good, i think it would be good to have a look at thatw the factory setup is a bit flimsy
http://aasilencers.co.uk/blog/tag/reliant-robin
?
I found that car via a google search some time ago, description sounds promising in the blog but not much visual details of any setup.
Need to see if i can reach him directly. His front end setup sounds good, i think it would be good to have a look at thatw the factory setup is a bit flimsy
Hey
Small update, nothing fancy, but i have a few more questions.
Here is a photo of the BMW rear axle frame, as you can see, in itself it is much wider than the Bug chassis, but still easily useable, i think :
After several measures, it turns out the outer mounting point for the BMW A-arm clears (beyond) the chassis rail, and the arm member itself runs parallel outside the rail, thus clearing it (and avoiding having to chop up and rebuild the upper member where the shocks fit and body rests)
Full bmw setup :
With that in mind, i was thinking of :
- working out the tyre diameter i'll be planning to use, and making mockup wood blocks to mimick the tyre height, thus setting the hub (and therefore diff) height.
That would :
- allow me to work out the trailing arm angle in relation to the mounting points on the rear bmw frame.
I'm thinking of using the same angle as the OE bug trailing arms ? Should pretty much put me in the correct setup as far as diff/hub/shock travel (and therefore wheel travel) goes ?
My idea is to notch the top of the Bug rails in order to "sink" the BMW frame member into them, based on the wheel height, bug trailing arms angle, and OE wheelbase.
Any thoughts on my theory ?
Thanks !
Small update, nothing fancy, but i have a few more questions.
Here is a photo of the BMW rear axle frame, as you can see, in itself it is much wider than the Bug chassis, but still easily useable, i think :
After several measures, it turns out the outer mounting point for the BMW A-arm clears (beyond) the chassis rail, and the arm member itself runs parallel outside the rail, thus clearing it (and avoiding having to chop up and rebuild the upper member where the shocks fit and body rests)
Full bmw setup :
With that in mind, i was thinking of :
- working out the tyre diameter i'll be planning to use, and making mockup wood blocks to mimick the tyre height, thus setting the hub (and therefore diff) height.
That would :
- allow me to work out the trailing arm angle in relation to the mounting points on the rear bmw frame.
I'm thinking of using the same angle as the OE bug trailing arms ? Should pretty much put me in the correct setup as far as diff/hub/shock travel (and therefore wheel travel) goes ?
My idea is to notch the top of the Bug rails in order to "sink" the BMW frame member into them, based on the wheel height, bug trailing arms angle, and OE wheelbase.
Any thoughts on my theory ?
Thanks !
The BMW axle slipped in pretty well, as you can see the trailing arms are just right alongside the outer flank of the chassis rails
9 inch Gotti rims originally from a R5 Turbo2
Track is now 175 cm (originally 123)
Its almost an equal sided triangle
9 inch Gotti rims originally from a R5 Turbo2
Track is now 175 cm (originally 123)
Its almost an equal sided triangle
Edited by Reliant on Wednesday 25th July 11:29
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