Rear suspension rebuild

Hi all...

I'm getting ready to rebuild the suspension on my 69 B. Since I'm so new at this and am not a mechanic by any stretch of the imagination, I thought I'd start with the rear first, just to build my confidence. My plan is to replace all rubber with prothane and install new shocks. Is there anything else I should consider since I'll have it apart? The springs are original but seem to be OK, just not real pretty (I've also read threads that replacement springs tend to have a tighter radius, thereby making the car sit higher). What about u-bolts , bump stop pedestal, etc?

And finally, a how-to question: I plan to support the body just in front of the forward spring mount, then support the axle with the jack. My question is, how much tension (if any) is in the spring in this position? Do I simply remove the shackle bolts and lower the spring while supporting the axle? I've searched for a thread detailing rear suspension work but haven't found anything yet...

Thanks for any and all advice...I'm hoping you all will talk me through this!

Paul

Hey Paul, Im in the process right now of my rear rebuild. There is a thread that was started by GlenP on a front suspension rebuid. I kinda jumped in with pics and such of my rebuild. I know he was going to do the rear also but I dont know if he continued the thread with that. My rear springs had just alittle tnesion on them when I loosened the U bolts. This was by no means a deadly amount. I just placed a jack under them and loosened the nuts. Also be sure and support the axle, dont rely on the rebound straps to hold it up....ITS HEAVY.I would say it dropped maybe an inch or so. The car was supported just in front of the front mounting bracket for the springs and I cut off the end of a 2X4 for a spacer. I completley removed my axle but I wanted to clean it up (POR 15 the heck out of it), replace all seals, rebound straps, checked the backlash and thrust washers. Check the brakes line for crimping, tow companies dont think about that stuff. I didnt replace the bump stops they were in good shape. Thats about it. Mikek

Paul,

it works the way you had thougt of and there are no real problems as long as the bolt at the front can be taken out and has not corroded solid inside te bushing.
If you have a little time before you start your projekt, lube it gently with penetrating oil for some days.
When selecting new bushes and pads, you should use the plastic ones at the shackels at the rear but all the others should be new rubber ones as going for poly bushings will only make the car louder and are not necessary, as long, as you do not intend ralleying or racing.
Bump stop pedstrials can be renewed, if they have signs of corrosion and newones fitted, as the U-bolts too. The self securing nuts mustbe renewed as the front bolts too. If there is slack at the damper rods, you should also have new rods on your list.
Also lube the nuts at the rebound straps at their mounts welded o the axle. They are prone to breake away with their threaded studs otherwise. New rebound straps should also be on your list of parts to exchange but buy the right length as there are two versions on offer or ask the board member 'Heartbreakhotel', who can provide custom made polyester straps at a good price too.

There are helpful pics in the DIY-restoration manual by Lindsay Porter and it seems to be a good idea to find one before you start your project.

Ralph

Hi Paul,
As Ralph was suggesting,
Consider replacing the rubber rebound straps with some nice nylon ones manufactured by Rusty (actually Brokenheart Studio, but I would guess if he took requests he could play Heart Break Hotel on the trombone):
http://sites.google.com/site/brokenheartstudio/home

Other related items:
Pinon seal, if its leaking badly
Axle seals, if leaking or you have to pull either axle for de-clunk
For de-clunking:
Fiber sun-gear washers
Copper spider-gear washers
Tension-pin
Rear plate seal, if its leaking
If you have the axle out its a REAL good time to replace the brake-lines if they have been crushed (Common) or are very corroded.

Since you've got it this far down :)
Replace u-joints and have shaft balanced

Did I mention new outer axle bearings?

On the other-hand, just replace the suspenion soft parts you were planning and forget all this!

Thanks all...I actually have the Lindsay Porter book, along with the Haynes Manual and the green Official MGB Workshop Manual. I keep reading all of them over and over. I've read Mike and Glen's front suspension thread several times as well...you guys did a nice job...that thread, with all the great responses from members, gives me hope!

I'm not sure how much elasticity is in the original rubber rebound straps, but I doubt there is any in a nylon strap...does that make a difference? It seems that many of the small parts are inexpensive enough that it is silly to not replace them. The shocks are a bigger ticket item but do have to be done. Any thoughts on replacing the springs? Mike, did you simply clean up your old ones? They look great in the photo!

Paul - did my full rebuild 2 years ago. Very do-able, just take your time. The nuts on holding my rebound strap were toast. If they break, you'll need to drill out the bolt (connected to the axel) and use a cotter pin/washer to hold the straps in. If that happens, drop me a PM and I'll send you some pics.

R

Paul.

If for any reason you plan to take the axle straps off, consider breaking the nut on the axle mount rather than trying to remove it. Unless it is willing to move from the get-go, they tend to break off. At a minimum, I would be getting under there a week ahead of time and putting your rust busting fluid of choice on all fasteners that will come apart.

Pete

I'll start with the penetrating oil today...is there a consensus as to the best one that's readily available? This afternoon I make up my parts list for Chris Roop...still trying to decide if I clean up the old springs or install new. The PO's painter oversprayed a lot so the advice has been to break out the wire brush, then maybe a shot of rustoleum.

The best penetrating oil? PB Blaster. It stinks to high heaven, but does a good job. You can get it at just about any auto parts place.

Paul, I'm about two weeks behind you. Ordered my springs from Brit-Tek and waiting for their arrival. Lot of good info so far, especially on the axle strap nuts. Starting the rust busting this afternoon. All the best, Bob

So the adventure begins...

I've given my order to Chris, ordered shocks from Peter, and doused all the fasteners with PB Blaster. I figure I'll give 'em a shot every day till the parts arrive. While I was under there, I removed my fuel pump and will send it off to Dave DuBois for solid state conversion. I also ordered a new gasket for the rear end since it looks like it's leaking a bit...going to have to get under there with a brush and try to clean off all the gunk...that'll be fun! I'll get killed if I track any of that crap into the house!

More to come...

Mikek31,

I often set jack stands in the same place you have them pictured and have not had a problem with it slipping, but I have wondered about it doing so. I like your little fix-it block of wood idea and I think I will give it a try. Did you profile it on the stand side to fit the contour of it? It looks curved on the right but flat on the left. Soft or hard wood? With the wide grain pattern on the left side it appears to be a piece of Spruce?

Yeah, x2 on placing the jackstands this way. For new leaf springs, maybe the easiest way to put tension on them for installation is by placing a floor jack or bottle jack underneath the spring and just pushing upward on it. This will cause the end-piece to slide right into place for bolting up.

So pinch the brake line going to the rear end, drop it out and haul it and the springs to the 1/4 wash. Bring it home clean to work on. Install the eye bushings and then bolt up the springs. Now attach the rear end to both springs. Next, jack the rear end into place and install the rear hangers. Last, connect that brake line and bleed; shouldn't take much if you pinched it off.

The best penetrating oil I have come accross is Kroil. It also reaaly smells bad but has rarely failed to complete the task assigned to it. I've never had a problem with placing the jackstands right before the rear springs. The trick is to lower the car very slowly while constantly checking that the the stands are remaing vertical. The nuts on the rebound straps will probably be hopeless so a nut buster should be used to remove them without harming the strap mounts. The threads can be cleaned up with a suitible die. RAY

The 50-50 acetone and auto transmision fluid is all over the internet as the way to go. Have not tried it myself. I did suggest to a co-worker and he was very happy with the results. Myself, I would have to know more about WHY? it would work.

Prior to this, I always used diesel fuel applied a week before the big job. Stinks, but cheap!

Pete

Peter, Scot Abbot wrote this about the WHY (it's on the link I posted):

>>Not too big a surprise. Acetone wets metal well, dissolves AFT, and it has very low viscosity (~.25 cp near room temperature). That means it wets the surface and can flow freely (quickly) into small crevices. Even with some ATF in it, it is still relatively low viscosity.
Kerosine and related fluids, on the other hand, although they wet the metal and rust surfaces well, have viscosities of about .8-1.3 cp,( and, of course, oils are hundreds of times more viscous), so they will work proportionately more slowly.<<

Cheers,

Glen

Hello everyone. This is my first post. This forum has been invaluable in helping me save time sorting out my 78B that I impulsively purchased over the summer.I thank you all. I finally found a subject that I feel strongly enough about to comment on instead of lurking and soaking up knowledge. I have used Free-All for almost 25 years. It is a bit pricey and I buy it by the case through the mail. I first used it in tear down of commercial jet engines. As you know the tail end of turbines get pretty hot, and this stuff worked wonders. I brought some home to put it to the acid test- my 62 TR4 parts car. Voila! no more snapping,stripping rounding ,heating etc.I usually handout a few cans out of each case to friends, neighbors etc. leaving more time for my own stalled projects. I was sure someone here would have mentioned this stuff. They must sell it to someone besides me. PS I also own Triumphs. (I had to get that off of my chest)

So far some great ideas...I've been using the PB Blaster for the last couple days but have not tried to loosen anything yet. John...can you provide a source for your Free-All product or is it readily available? I'm sure there are plenty of folks who'd like to try it...I think I'll try to loosen a few nuts today to check the progress of the of the PB Blaster...if necessary, I'll start with the acetone and ATF...more to follow!

Thanks, Paul

http://www.freealloil.com/

Paolo, check your PMs.

So I started taking things apart today. The PB Blaster seems to have worked pretty well. No problems with anything so far...even luck out on the nuts for the lower rebound straps...came right off without a hitch! I found that my right shock had been leaking profusely (gee, I never could figure out that clunking sound when I went over a bump...duh!) but the left was good...new (rebuilt) ones are on their way. One of the shock links seems a bit dodgy...when removing the lower nut, the whole stem just spun inside the ball...took a while and a lot of expletives to finally coax it off. I'm assuming that ain't right, and that I should replace the links as well.

Next step is to actually remove the spring(s). More to come...

Paul

OK...so the first spring is off (doing one side at a time), I've hit it with the wire wheel, and I plan to shoot it with some Rustoleum or some such paint. My current problem is getting the old front bushing out and the new one pressed in. I tried the two socket routine in the vice, but I guess I have a pretty wimpy vice. I've been hitting it with PB Blaster, but I'll probably have to take it somewhere and have it done. Any ideas? Thanks...

Since you have already tried the idea I just emailed you, you might try getting ahold of DB Wood.

I am a couple of days ahead of you. Luckily we had a small press at work and with a socket the bushing came out easily. If you need to replace the Delrin strips between the leaf springs try Speedwaymotors.com. One 20" roll is just short of doing two springs.

Paul, You're still a little bit ahead of me and I appreciate all of the info coming in as a result of your efforts. My first spring comes off this weekend. Regarding the old front bushing (now this may be a real bad idea for reasons that I cannot fathom, but it worked). I did a Corvette a few years ago and found it easiest to burn the old rubber bushing out with an acetylene torch (cheap one that you can pick up at any hardware). Burn the rubber and pry it out piece by piece. Then I cleaned up the pieces, preserved and painted and then pressed in the new bushing. It was a PITA, but it worked and the car drove well for many years after that. Bob

I thought I'd update this thread: I'm coming into the home stretch. I have all parts cleaned and mounted back on the car. I still need to do final tightening on the U-bolts and shock links. Also need to fill the rear end with 90 wt. and won't bother to bleed the brakes till I'm done with the front suspension. I cleaned the rear axle by hand, then painted it, but horsing it back by myself scuffed it up a bit...oh well, it is a driver after all!

On most of the parts I used a wire wheel and POR15...in retrospect, I wish I'd had everything blasted then powder coated...I just didn't have any way to transport the rear axle. POR15 is a good product, but my results were less than stellar...some runs and streaks, but all in all not too bad. When painting the rear end, I just went over the existing paint which was solid (yea I know that the POR folks don't like that), but had some runs in it...so of course they showed up again.

So now I have rebuilt shocks, prothane bushings, new shock links, new U-bolts, new bump pedestals, new rebound straps, and lots of new nuts and bolts. I've also decided to get a new brake cable as well as new lever boots. It seems as though one thing leads to another...I'm sure you're all familiar with that! I'm also waiting on my fuel pump from Dave DuBois...should be here in a couple weeks.

So I want to thank all of you for your suggestions and support. I actually feel like I can tackle the front suspension next! I'll post a few "before" pics then some "after" pics...

Here's another...

One more...

Now a couple "after" shots...

Rear end after painting...

Here's the last one...

Thanks again for your help...this is a great forum!

Paul,
It looks great, too bad our weather isn't co-operating so you can tear up the roads. When we get some decent weather you can bring it over and put it up on my lift to check out the front end.

Hi Dan...

We've got about 6-7" at the house now...been snowing all day! Not sure when I'll be taking "Snowflake" out for a spin. I imagine you're finally done working for while? I'll send a PM later to chat about requirements for the front project. Thanks again for all your advice...for my first project on the car, it was enjoyable and I'm pleased with the results...

Paul