Installing Randy Forbes Subframe Kit

[Randy Forbes]

Will do, thanks.

Everything is still in the shipping box; I just pulled the steel pieces out to confirm everything looked right. I was really only looking for the impulse wheel, and that was definitely there. I didn't know I'd be getting bolts as well.

The only thing it seems I've lost is my mind!

There are (or were...) a pair of flanged-head bolts, washers & flanged all=steel locknuts taped to the cut-steel reinforcement pieces, between the 13" long longitudinal plates (folded lengthwise) and the pair of pendants.

Edit: the bolts are M12 x 1.75 x 40mm long, along with associated hdwr. The local ACE Hdwr__with an entire isle of compartmented/assorted hardware carries these.

[s8ilver]

There are (or were...) a pair of flanged-head bolts, washers & flanged all=steel locknuts taped to the cut-steel reinforcement pieces, between the 13" long longitudinal plates (folded lengthwise) and the pair of pendants.

Edit: the bolts are M12 x 1.75 x 40mm long, along with associated hdwr. The local ACE Hdwr__with an entire isle of compartmented/assorted hardware carries these.

Thanks Randy, I'm sure they're still there (didn't pull off anything taped on)...I got the package a while back and then traveled for a month. After that adventure (Lufthansa went on strike halfway through my outbound trip, then experienced the worst rain in India in over 100 years, then got sicker than I've ever been in my life), I'm just glad I remembered where I parked my car.

[ProductUser]

The subframe reinforcement welding was completed this morning. The welder said the reinforcement kit was well made.

The welding shop allowed me to work with the welder through each step of the process, which was pretty cool.

Now I can remove the differential to replace the impulse wheel and begin the prime/paint/seam sealing work

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[Mark Bielick]

One question. On your picture showing the differential cover, it appears there are 3 rivets along the left side of the reinforcement attachment, where the spot welds normally failed. I'm assuming they were temporary rivets to hold things in place during welding.

Mark

[ProductUser]

One question. On your picture showing the differential cover, it appears there are 3 rivets along the left side of the reinforcement attachment, where the spot welds normally failed. I'm assuming they were temporary rivets to hold things in place during welding.

Mark

Correct. I used a few steel rivets to pull a small gap between the trunk floor and crossmember together before welding.

Tony

[ProductUser]

Removed the differential today. Also continued priming the forward part of the cross member now that the differential is out.

The differential goes to a shop tomorrow to have the smaller impulse wheel installed and have all of the seals replaced. I decided not to undertake this job.

Seam sealing begins on Wednesday.

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[Muzz258]

I was wondering how you got the two top diff bolts out, answered by your most valuable tool. When you use this tool to tighten up the bolts, how does its use impact on the setting you dial up on the torque wrench?

Have you already installed plastic sub-frame bushes (IE, Power Flex or other)? What are the trailing arm bushes like? Is this work something you should be considering now when removing the sub-frame would be a relatively easy task?

[BimmerBreaker]

I just realized your location! I just locked down my next home which will be in Mesa...! I'd love to see it when its done, maybe we can do a little drive somewhere with some other local Z3 guys I know.

[ProductUser]

I was wondering how you got the two top diff bolts out, answered by your most valuable tool. When you use this tool to tighten up the bolts, how does its use impact on the setting you dial up on the torque wrench?

Have you already installed plastic sub-frame bushes (IE, Power Flex or other)? What are the trailing arm bushes like? Is this work something you should be considering now when removing the sub-frame would be a relatively easy task?

Check out this link around torque adjustments.

The bushing look okay. They are 15 years old and should be replaced just on time alone. I don't track this car, so I may just leave them alone. Thanks for putting that thought in my head

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I just realized your location! I just locked down my next home which will be in Mesa...! I'd love to see it when its done, maybe we can do a little drive somewhere with some other local Z3 guys I know.

Definitely!

I live across the street from Leisure World. Yeah, that's right! Leisure World

[ProductUser]

Have you already installed plastic sub-frame bushes (IE, Power Flex or other)? What are the trailing arm bushes like? Is this work something you should be considering now when removing the sub-frame would be a relatively easy task?

I ordered the IE subframe and trailing arm bushings yesterday. Thanks for the push , Muzz258

[Mr Bingley]

I ordered the IE subframe and trailing arm bushings yesterday. Thanks for the push , Muzz258

Hopefully you ordered OEM trailing arm bushings and not urethane trailing arm bushings--if you did order urethane trailing arm bushings, order and use the OEM bushings and return the urethane ones when they arrive. The urethane trailing arm bushings squeak quite annoyingly. I.E. Subframe bushings are the correct replacement. There are a couple of special tools associated with these jobs--have you looked into these?

[ProductUser]

Hopefully you ordered OEM trailing arm bushings and not urethane trailing arm bushings--if you did order urethane trailing arm bushings, order and use the OEM bushings and return the urethane ones when they arrive. The urethane trailing arm bushings squeak quite annoyingly. I.E. Subframe bushings are the correct replacement. There are a couple of special tools associated with these jobs--have you looked into these?

Thanks for the information regarding the squeaking urethane trailing arm bushings. I'll order the OEM trailing arm bushings.

I did read about how to create the special tool(s) to remove the old subframe and trailing are bushings. I'm off to my home store tomorrow to buy the needed materials to make the tools.

Many thanks!
Tony

[s8ilver]

Thanks for the information regarding the squeaking urethane trailing arm bushings. I'll order the OEM trailing arm bushings.

I did read about how to create the special tool(s) to remove the old subframe and trailing are bushings. I'm off to my home store tomorrow to buy the needed materials to make the tools.

Many thanks!
Tony

I had to search high and low for that 3" pipe nipple and cap, but the rest is Home Depot. Some had quoted around $25 for all the bits. Just the pipe parts ran me $40. Oh well, beats the $600 BMW tool.

[ProductUser]

I had to search high and low for that 3" pipe nipple and cap, but the rest is Home Depot. Some had quoted around $25 for all the bits. Just the pipe parts ran me $40. Oh well, beats the $600 BMW tool.

I read your post re making this

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After two very uneasy visits at a local BMW and differential shop to have the impulse wheel replaced, I decided to take on this task after all.

The only part that remains is replacing the seals and reassembly. It's not that bad of a job.

I needed a place free from blowing dust, so I did everything on the kitchen floor

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[couchflyer]

If you post no more, we'll know why!

[Adker]

I read your post re making this

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After two very uneasy visits at a local BMW and differential shop to have the impulse wheel replaced, I decided to take on this task after all.

The only part that remains is replacing the seals and reassembly. It's not that bad of a job.

I needed a place free from blowing dust, so I did everything on the kitchen floor

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Understanding wifes are worth their weight in gold!!

Merry Xmas

[ProductUser]

While the differential is waiting for some Red Line gear oil to arrive, I decided to look at replacing the subframe bushings (IE subframe bushings in-hand).

I read a few threads around the procedure to replace the bushings; however, I'm not sure I want to take this on (I said the same thing about the differential work, too, and ended up doing the work myself )

The OEM bushing is fried.

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[Muzz258]

Its not too bad a job. You've got your 3" pipe tool. Make sure you have some type of gas heating torch to heat housing to soften the rubber and make it easier to pull the bushing. A hot air gun is not good enough. Remove the sub-frame before you attempt to remove the bush, because you will be using a gas torch and the right hand bush is just too close to a plastic gas tank.

I used a different design of pulling tool that works on the same principals as the 3" pipe tool. The key was heating the housing so that the rubber was hot and just starting to smoke (no flames), then it pulls out easily. You will need to clean up the heated area of the housing and give it a coat of paint when finished.

Having the sub-frame out makes the replacement of the trailing arm bushes easy too. Search You-tube for a clip that shows the use of an impact gun to pull the bushes with a length of 1/2" treaded rod and nuts and washers. Think it was a BMW E30 clip? I used a couple of spanners and used this method to easily remove the bushes. Press the new bushes back in with with "G" clamp or similar. I took my vice off he bench and used it to press the bushes in.

[JustinHalverson]

Its not too bad a job. You've got your 3" pipe tool. Make sure you have some type of gas heating torch to heat housing to soften the rubber and make it easier to pull the bushing. A hot air gun is not good enough. Remove the sub-frame before you attempt to remove the bush, because you will be using a gas torch and the right hand bush is just too close to a plastic gas tank. I used a different design of pulling tool that works on the same principals as the 3" pipe tool. The key was heating the housing so that the rubber was hot and just starting to smoke (no flames), then it pulls out easily. You will need to clean up the heated area of the housing and give it a coat of paint when finished. Having the sub-frame out makes the replacement of the trailing arm bushes easy too. Search You-tube for a clip that shows the use of an impact gun to pull the bushes with a length of 1/2" treaded rod and nuts and washers. Think it was a BMW E30 clip? I used a couple of spanners and used this method to easily remove the bushes. Press the new bushes back in with with "G" clamp or similar. I took my vice off he bench and used it to press the bushes in.

Also make sure you use a big washer that will sweep out the entire old bushing. Too small a washer and you can leave the outer portion of the bushing in the subframe, including a metal cylinder encased in partially melted rubber. Ask me how I know. My stupidity is all documented elsewhere on this forum. ?

[ProductUser]

Also make sure you use a big washer that will sweep out the entire old bushing. Too small a washer and you can leave the outer portion of the bushing in the subframe, including a metal cylinder encased in partially melted rubber. Ask me how I know. My stupidity is all documented elsewhere on this forum. ?

Thanks for the information, guys. I've read and watched quite a few threads on various ways to remove the subframe bushings, including melting the bushings

I'm not going to remove the entire subframe, due having to bleed the break lines. Using a torch is not something I want to attempt in my garage. If something goes wrong, I will be living the rest of my days in a doghouse if I'm lucky I will use the 3" pipe method, though, with the subframe lowered as others have done.

While I give this more thought over the next few days, I will start putting the trunk back together.

Thanks for the tip about cleaning out the old bushing remnants.

[JustinHalverson]

I used a hot air gun. Together withe the right sized washer it worked fine on the second bushing. Just make sure you run it at the highest temp for a long time.

[Muzz258]

You may need to rethink your decision on leaving the sub-frame in the car. The IE bushes are in two parts and you may need to drop the sub-frame past the length of the break flexible hoses to fit the top sections. Others who have fitted these bushes can advise you better than I can.

The break hoses are easy.
1) Use a piece of wood to hold the break pedal down, wedged lightly between the seat motor and the break pedal. This will stop the break fluid from draining through the master cylinder onto you floor. Seriously one or two drops at the most.

2) Separate the break hoses at the joint between the solid and flexible joint

3) When reassembling, get a friend to help with bleeding the breaks. Only a couple of pedal pushed per wheel as you've had that wood stick wedged as per step one. You will need a good 7 mm ring spanner to be able to open the bleed valve on the calipers.

The sub-frame is a large thermal sink and will suck a lot of heat. I tried a hot air gun and after 10 minutes had not got the bush hot enough. Could have been the 2000 W hot air gun or my impatience. Purchased a gas torch and the bush was hot enough in less than 5 minutes.

I was playing the heat on the circular metal outside of the bushing housing. Not directly on the rubber bush. Wanted to mainly heat the rubber in contact with the housing and not the internal rubber which could cause it to break and leave the outer of the bush in place.

[Randy Forbes]

With an M Rdstr, you have the luxury of NOT disturbing the BRAKE (it's BRAKE!) hydraulic circuits. If you want to take the suspension carrier out of the car, just take the two (2) bolts out of each caliper, the ones from the caliper to the mounting bracket (Allen head bolts under the black plastic caps) and hang them with a piece of wire to the exhaust mounting brackets on the body.

Z3s on the other hand, with their four (4) flex-lines are just a pain in the butt; as bad as the M3s...

[RedRedZ]

PSA:
Break means: To damage: "If I hear your phone ring one more time, I am going to break it."
To separate: "I will break off a piece of this cookie so you can taste it."
A pause or period of rest: "I will turn off the computer and take a break."
To infringe or disobey: "That is an unfair rule, and I am going to break it."

Brake means:
To stop or slow: "The large pedal in the floor is how you brake the car."
The mechanism to stop a vehicle or machinery: "I had to press the brake pedal to keep from hitting the deer."

[325bimmer]

Weo weo weo...grammar police! Ha! I too am bothered by misuse of words and I know that homonyms litter internet postings! I have tried (as painful as it may be) to just let them be and focus on the meat and potatoes of the post.