MyE28.com

Hi all,
First time posting here and I hope you forgive an E24 interloping on E28 turf.
Here's my situation: Am delivering my car (1985 635CSi 5 Sp) to TCD in late April for a stage II install of their kit as Todd has kindly consented to do it. I will leave the car with him for a couple of weeks and then fly back in from Montreal and drive out.
He is planning to tune the car to about 12 psi.
Car is in good shape with about 110,000 miles on it , dry compression check done just before the car went into winter storage measured 160 on all 6 cylinders, doesn't burn any oil (synth) or go through any coolant at all between regular changes.
Todd and I have discussed upgrading the clutch so it can handle all the extra torque /.ponies soon to (happily !) be available. I just had a new OEM Sachs clutch installed 3 years / 15,000 miles ago.
We also discussed him installling a solid steel head gasket and ARP head studs as a preventative measure.
My dilemna is that I am at the outside of my financial envelope so to speak with just the stage II and can afford at this time as an additional immediate expense only the head gasket upgrade or the clutch upgrade but not both. By the end of the summer I'll be financially able to do the second upgrade if necessary.
Todd has given me about as honest an opinion on the necesssity /desireability of both upgrades as he can which basically comes down to that it is impossible to be sure .
I spent some very educational & entertaining time this past weekend reading through yr recent posts but I was kind of freaked out to read one recent poster's remark that his stock clutch lasted 2 weeks (!) post TCD install. So I know I am asking a question here with no black and white answer but would very much appreciate any advice or opinions or experience .
Which upgrade would you choose to do now in my place ?
Thanks

The short answer is: you need both. I would suggest doing the clutch now. You will need the headgasket/studs, but hopefully you can get by until you've got the cash. Don't plan to run any big boost on the stock headgasket and get away with it.

I'd wait on the clutch. It's much easier to change out a clutch than it is to change the head gasket after all the turbo stuff has been installed. Also, if the clutch starts to slip over time you can still drive the car around... not so if you squeeze a head gasket out the side.

Hi Taylor,

I'm with Sweeney for a few reasons.

1. While you are at Todd's shop and the turbo is going in, the head job is the easiest that it will ever be.

2. Any good shop in Montreal can do you a clutch. Take in a turbo car with a head gasket gone, ask for ARP studs with a Steel Head gasket and you are going to want to drive (tow) the car back to Todd's .

3. If you are good, the clutch will last a while and then it will fail in a predictable way, start to slip ..... and then you turn the boost way down .... life goes on until you schedule the job. When you blow the head gasket, you park the car and cry.

Just so you know, I did the clutch first....that's why I know!

From a fellow Canadian running a solid 15 psi boost on a custom clutch by a guy in Burlington. The ARP's went in first time I did the head. I used the wrong head gasket, so I did the head again.....but then I am not very smart and spend a lot of time on the race track. It will be completely dependable and when done correctly...

Cheers,
Dave

You really do need to do both. Talk to Todd about it, maybe he'll do it all for you now, and let you slide on the clutch for a little while. I'm pretty sure it's much more convenient for him to do everything at once, rather than have to take the car back apart in a month or two. I'm taking my car to him in a few weeks (1 week before you) and I'm getting both things done at once, as well as a 533i flywheel and new starter. Best of luck to you!

Agree w/ Sweeney. Knowing the problems you'll encounter you can be proactive to some degree and be as gentle as possible on launches and avoid low-speed romps on the loud pedal. You can probably make the clutch last a few months if you're careful. And as has been noted, anyone can change a clutch; you don't want just mucking around with your new turbo motor.

-tammer

e mail to Todd and ordered up the gasket / stud job as an add on.
I'll try to jolly the stock clutch along for a while and see what happens. I do have a good shop right here in Montreal two blocks from my flat who can easily ( just throw money at them and poof ! it's done ) install the clutch. Going to be hard to refrain from stomping on the gas but will try !
I just hope it doesn't go out on me in Cowphart, Ontario on the way home....

Taylor '85 635CSi A 5 sp. wrote: I just hope it doesn't go out on me in Cowphart, Ontario on the way home....

As has been said, it's not going to die suddenly. If you feel it slipping, you'll just have to baby it all the way home. You shouldn't get stranded unless you do something dumb.

Clutches in these cars aren't known to blow apart under stress, so it's very unlikely to leave you stranded. Even clutches that proved inadequate under dyno stresses (slipped) were perfectly driveable on the street afterwards. You made a good decision IMO.

Jeremy

What I would do is the Head Gasket as well, for all the reasons above.

the other thing is after Todd is done tunning the car up to 12, 13, 14 psi or whatever, you should turn the boost down. This will help keep the clutch alive longer, and it will help you get used to the boost. I would start with 6psi. after about a month raise it a little to like 8psi. and so on
The car will act differently and you must get used to it anyway.

Um, what,
Im not sure I agree. While the turbo is being installed, you can install the gasket/studs, but its not major. You don't remove any of the hard stuff when installing a turbo, right? You just remove the exhaust manifold. As I see your not pulling stuff off the head involved with coolant, or the wiring harness or the intake manifold.

Now, maybe Im off base, but the stock gasket is OK for 12psi, right? As long as you don't overboost or pre-detonate, it should last many miles, even longer than the clutch easy. You do have a 8:1 engine, so your not running super high BMEP. Most here blow out head gaskets from pressing the boost envelope, and 12psi ain't that, trust me. My car went 30k miles at 12-13psi. But didn't blow until I started the tuning process and pushing the psi up and un-fortunately some pre-detonation.

Im leaning towards the clutch, as you'll really want to use that 375lb-ft of torque, trust me.

There should be plenty of shops that can do a head gasket install, I hope.

My .02

RussC