E30 325i Cabrio - improving brake performance

E30 325i Cabrio - improving brake performance

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Discussion

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
I have owned this car from new and used to eat through pads and disks at a regular rate.

On Tuesday, I was taking it to my garage for the suspension to be replaced after winter layover. I was driving at 60mph towards the local Range Rover dealership who had parked display cars along the nearside kerb. A Jaguar saloon, pulled out so that he could see past the parked cars and was perfectly placed so that I could T-bone him in the driver’s door. I stood on the brakes and not much happened, hydraulics pushed pistons, but no ABS rattle, just gentle retardation.

I thought that I was about to get seriously hurt, but guessing that I had probably slowed to about 30mph, managed to swerve round him without clipping the corner.

My garage has now replaced the discs and pads and says that now they are ‘not bad”. I am not reassured, I would prefer that they are perfect. As I am sure that with either of my other cars, I could have stopped in a straight line.

I think the original hydraulics are ATE, I think I can get an ABS master cylinder, but not callipers.

Has anyone done, or able to recommend, any sensible upgrades without going to a track spec? The car is normally driven sedately with the top down, but I have to have a car that can do an emergency stop, when needed.

Thanks for your thoughts

trevalvole

1,042 posts

34 months

Sunday 12th May
quotequote all
rdjohn said:
I think I can get an ABS master cylinder, but not callipers.
I've seen tv programmes where they get the callipers refurbished, so that might be an option.

d_a_n1979

8,629 posts

73 months

Sunday 12th May
quotequote all
rdjohn said:
I have owned this car from new and used to eat through pads and disks at a regular rate.

On Tuesday, I was taking it to my garage for the suspension to be replaced after winter layover. I was driving at 60mph towards the local Range Rover dealership who had parked display cars along the nearside kerb. A Jaguar saloon, pulled out so that he could see past the parked cars and was perfectly placed so that I could T-bone him in the driver’s door. I stood on the brakes and not much happened, hydraulics pushed pistons, but no ABS rattle, just gentle retardation.

I thought that I was about to get seriously hurt, but guessing that I had probably slowed to about 30mph, managed to swerve round him without clipping the corner.

My garage has now replaced the discs and pads and says that now they are ‘not bad”. I am not reassured, I would prefer that they are perfect. As I am sure that with either of my other cars, I could have stopped in a straight line.

I think the original hydraulics are ATE, I think I can get an ABS master cylinder, but not callipers.

Has anyone done, or able to recommend, any sensible upgrades without going to a track spec? The car is normally driven sedately with the top down, but I have to have a car that can do an emergency stop, when needed.

Thanks for your thoughts
Are the calipers working ok? That'd be my first port of call - you could look to get fully refurbed ones from the likes of Brakes International or a full refurb kit from the likes of Bigg Red

That; with decent discs and pads (ATE blanks with a more aggressive pad maybe, Ferodo DS2500s or similar) with HEL braided lines and a full fluid flush & refill should hopefully give you a much better braking set up and better brake feel

Have you Googled to see what the OEM 'big brake upgrade' could be (ie bigger brake calipers, discs etc from another BMW retrofitted)


InitialDave

11,978 posts

120 months

Sunday 12th May
quotequote all
Hmm, that certainly doesn't sound right, the stock brakes in good condition should haul you up just fine.

I assume you want to keep the car as-is with a 4 bolt hub, yes?
And does it have 14"/15" standard wheels or aftermarket larger ones?

That's going to set the restrictions you're operating within for upgrades.

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
Hi, thanks for the information

Whenever I have done brake reseals (a very long time ago), it was always the piston corrosion that was the biggest issue. Biggred have the seals, but no pistons, Brakes Int. have pistons and seals from Budweg, who I have not heard of.

You have me wondering about the flexible hoses being the real problem when I stood on the pedal. Hopefully, I will get the car back tomorrow, and gently run-in the new pads and then have a big rethink.

I do not want to sell the car after so long, but then I never want to relive/die the experience that I had last Tuesday.

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
InitialDave said:
Hmm, that certainly doesn't sound right, the stock brakes in good condition should haul you up just fine.

I assume you want to keep the car as-is with a 4 bolt hub, yes?
And does it have 14"/15" standard wheels or aftermarket larger ones?

That's going to set the restrictions you're operating within for upgrades.

I want to keep the car original, after so long. As you say in 1990, the brakes worked fine and it was driven much harder then.

I am looking to get the brake performance as close to original as possible.

williamp

19,280 posts

274 months

Sunday 12th May
quotequote all
Are they bad, or normal (brakes have improved massivly over the years). All mot testing stations have brake testing equipment. I'd be tempted to get in on the rollers and ask them to test the brakes. Youd know if they are all bad, or just ome axle..

InitialDave

11,978 posts

120 months

Sunday 12th May
quotequote all
OK, looks like 14" bottlecaps to me, so I think going any bigger on discs or upgraded calipers isn't going to be viable.

I would have the calipers refurbished with seals and pistons, replace the flex hoses and have the hardlines checked (the rear ones are sandwiched between the fuel tank and the shell iirc, which is a pain), and fit decent quality discs and pads, properly bedded in (I favour the "multiple hard brakings from decent speed without actually coming to a stop" technique).

E30 standard brakes should certainly work well enough for the usage you've described.

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
williamp said:
Are they bad, or normal (brakes have improved massivly over the years). All mot testing stations have brake testing equipment. I'd be tempted to get in on the rollers and ask them to test the brakes. Youd know if they are all bad, or just ome axle..
From new they easily triggered ABS if I stood on the brakes. For the first 10-years, I frequently warped the front discs.

On Tuesday, my first reaction was that I had sufficient distance to stop. I merely slowed down a bit.

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
Budweg are Danish. I did not know that they had an automotive industry.

d_a_n1979

8,629 posts

73 months

Sunday 12th May
quotequote all
rdjohn said:
Hi, thanks for the information

Whenever I have done brake reseals (a very long time ago), it was always the piston corrosion that was the biggest issue. Biggred have the seals, but no pistons, Brakes Int. have pistons and seals from Budweg, who I have not heard of.

You have me wondering about the flexible hoses being the real problem when I stood on the pedal. Hopefully, I will get the car back tomorrow, and gently run-in the new pads and then have a big rethink.

I do not want to sell the car after so long, but then I never want to relive/die the experience that I had last Tuesday.
Budweg have been around a long time. Used their parts to refurb many JDM Honda brake calipers with zero issues...

Do Brakes Int have your calipers in stick, as that'd be an easier exchange?

Braided lines make a good different of feel, but they'll give you the same braking power as you've got now. IIRC only a bigger master cylinder will change that.

But new pads and discs needed to be bedded in really. They can feel soft to begin with. Have you done that?

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
I will get the car back on Tuesday and a bit of bedding in time, before I go to France at the end of the month. Unfortunately I cannot devote much time as moving house at the moment.

Brakes int. show calipers as out of stock. If I go down that route I will check if they can get them.

Perhaps the brake lines only swell when you stand on the pedal. Just a thought.

d_a_n1979

8,629 posts

73 months

Sunday 12th May
quotequote all
Your brakes lines shouldn't swell that much. How old are they?

How llds the fluid as well? If that's old that can be detrimental also

rdjohn

Original Poster:

6,231 posts

196 months

Sunday 12th May
quotequote all
I suppose a problem is it only does perhaps 5-6k miles every year, so servicing is pretty ad hoc. Tending towards - need to do.

So the answer is I have no idea, maybe never! A good example is the cam belt. Every 50k, or 5-years. Cant remember exactly when it was last done, but I am pretty sure it was before 2019. That was also done last week.

The brake fluid has now been replaced, but I usually ask for that to be done fairly frequently. When I fired up this year, most of the clutch fluid had gone. But just topped it up and it is OK. that has now been flushed.

Perhaps I need to keep a check on what has been done, and when.

d_a_n1979

8,629 posts

73 months

Sunday 12th May
quotequote all
Before you do anything try bedding in the brakes again...

Quiet second of a bypass tonight if you can with it being a Sunday.

Up to 70, brake hard but safely down to 40 and repeat a few times until they're biting better then drive around for 10mins or so normally to let them cool off and then see how they act after that

The Conflated Outlier

51 posts

14 months

Sunday 12th May
quotequote all
The standard brakes are fine for a 325i - if they are working properly.

Look on ebay and you have a choice of reconditioned calipers - you mentioned Budweg earlier and they were always a good brand. Four calipers and new brake hoses are a good start, plus discs and pads if they are way past their best. Glazed discs/pads tend to squeal. Original 1988 brake hoses will likely be trying to heal up internally by now.

If the master cylinder was faulty the pedal would sink to the floor and you'd have air in the system. It could be a stuck valve in the ABS pump but those old Ate Teves units were pretty good. A good used one won't cost much if it is knackered.

One of the big complaints about E30 brakes when they got old was the amount of pedal travel and a resulting poor feel to the brakes. That was down to some play in the cross linkage from the pedal box to the master cylinder/servo. It's very easily fixed - you drop down the glovebox and the drivers undertray so you can access both ends of the cross linkage pushrod. Slacken the 17mm locknut on each end and turn the pushrod (I think it was counter clockwise).
You'll see the brake pedal rise. Adjust it up about an inch or the same height as the clutch pedal and see how it feels. This always made a big difference.

d_a_n1979

8,629 posts

73 months

Sunday 12th May
quotequote all
The Conflated Outlier said:
The standard brakes are fine for a 325i - if they are working properly.

Look on ebay and you have a choice of reconditioned calipers - you mentioned Budweg earlier and they were always a good brand. Four calipers and new brake hoses are a good start, plus discs and pads if they are way past their best. Glazed discs/pads tend to squeal. Original 1988 brake hoses will likely be trying to heal up internally by now.

If the master cylinder was faulty the pedal would sink to the floor and you'd have air in the system. It could be a stuck valve in the ABS pump but those old Ate Teves units were pretty good. A good used one won't cost much if it is knackered.

One of the big complaints about E30 brakes when they got old was the amount of pedal travel and a resulting poor feel to the brakes. That was down to some play in the cross linkage from the pedal box to the master cylinder/servo. It's very easily fixed - you drop down the glovebox and the drivers undertray so you can access both ends of the cross linkage pushrod. Slacken the 17mm locknut on each end and turn the pushrod (I think it was counter clockwise).
You'll see the brake pedal rise. Adjust it up about an inch or the same height as the clutch pedal and see how it feels. This always made a big difference.
Wow; that's hell of an insight for the OP! Hopefully that'll get the brakes biting/feeling better

d_a_n1979

8,629 posts

73 months

Sunday 12th May
quotequote all
HEL braided lines here FYI:

https://www.ebay.co.uk/itm/202563683531?epid=10027...

Bit like the E38s with 6 lines...

rdjohn

Original Poster:

6,231 posts

196 months

Monday 13th May
quotequote all
Thanks to everyone for your kind help.

There has to be a good solution in there.

I have thought for some time that the pedal travels too far. It feels solid before the engine is fired up but the servo seems to make it feel soft.

As someone mentioned, brakes on modern cars seem so much better.