July 19, 2009 at 9:06 am #232684
I do not have records of exactly what was done during the install of the rear suspension of my CMC Chevette MG TD. It has the expected coil springs with internal shock. But I don’t know if the springs had been cut down or whether it has the correct shock absorbers.
My problem is that the rear end rides a bit lower than I suspect it should and bottoms out on even moderate undulations in the road. Put two adult size people in it and it bottoms out almost totally.
Is there a simple way I can determine if the springs are correct (eg, should they have a specific number of coils, etc.)? And what part number is correct for the shock absorber. The online copy of the build instructions calls for a shock PN: TRW 80802 but I’ve yet to find that number cross referenced anywhere online. I’m wondering if the prior builder had put an incorrect shock in there which is actually the component that is bottoming out.
I’ve looked underneath while someone bounced on the rear of the car and there does not appear to be anything visible that is bottoming. But if it is the shock itself it would not be visibly apparent. I will have to remove a shock to measure whether it is hitting the limit of its travel.
Just looking for thoughts and suggestions. Or perhaps it is normal for these rear suspensions to behave this way?July 19, 2009 at 5:31 pm #239313Steve CritesParticipant
With 2 people my chevette rear bottoms out on occasion. Sometimes on bumps that I think are not that bad. I had wondered about a fix myself. Shocks seem to work OK, but maybe the springs are worn or wrong cut?
Hopefully maybe someone will enlighten us on a fix (or a diet that works)
RingoJuly 19, 2009 at 5:58 pm #239314James CochranParticipant
I am thinking of replacing my shocks with adjustable Koni’s. It helped on my other sports car for bottoming out, but I don’t know if this is a solution to your suspension. We have some members that know a great deal about the suspensions. The Koni shocks maybe just a bandaid fix, but it has helped for better than 25 years so far on my other car (67 Datsun Fairlady Roadster).
JamesJuly 19, 2009 at 7:20 pm #239315
Does anyone know a current shock PN (Koni adjustable would be really great) that are bolt-in fits for the CMC Chevette MG TD?
I’ll be happy to be among the first to try them in this application if I can be reasonably sure I’m buying the right ones.
Anyone have a modern cross reference for the CMC specified TRS 80802 shocks? Or maybe the specs (dimensions) of those?July 20, 2009 at 8:39 am #239316Rob BakerParticipant
Hawk, perhaps just replacing the tired springs would help. I replaced my leaf springs on my ford based product and it resolved my bottoming out. I considered adding coil over shocks as well but have other priorites at the moment.July 20, 2009 at 10:16 am #239317
Larry Murphy has brandy new rear coils that he may be interested in selling to you.
Chevette rear springs and shocks are still available (MOOG, AC Delco, Raybestos, Husky, etc.) http://www.rockauto.com
Also, shocks WILL NOT stop a bottoming out situation. Shocks only dampen spring oscillation and keep the tire in contact with the road.
KYB makes a really nice shock (Gas-A-Just or G2), also available on http://www.RockAuto.com. Be careful though…a too stiff shock will ruin the ride on these light cars.July 24, 2009 at 8:00 pm #239318
Pulled a rear shock off this evening. At the normal “ride height” the shock rests at 10 inches (between the base of the stem at each end of the shock). Fully collapsed the shock measures 9 inches.
Thus, there is only 1 inch of compression travel before the shock bottoms out solidly. This is the hard BUMP I’ve been feeling on modest undulations in the roadway.
At least one of two things is true. Either the original builder put the wrong shocks on it. Or he didn’t mount the shocks as they were intended to be mounted. Or both. Each end of the shock appeared to be mounted securely with a pair of rubber bushings with metal caps. But I’m not even sure the correct shocks utilized a stem mount on the top AND bottom. Or do they?
My shocks are the ‘stem type’ on both ends. They are stamped with a part number of LE10006 and another number PF15T1E. Collapsed length 9 inches. Fully extended 14 inches.
I’m hunting on the internet for a similarly designed shock that is no longer than 8 inches when fully collapsed. 7 1/2 would be even better. I’d like to get at least 2 to 2 1/2 inches of compression before it bottoms out. If I _have_ to I’ll rework the frame and lower mount to extend the travel of these shocks. But that’s a LOT of work for someone w/o a real shop.
Does anyone out here happen to have one of the correct CMC Chevette rear shocks that you could measure for comparison? I need the distance between the base of the stem at top and bottom ends when the shock is fully compressed. Ignore the mount bushings. Or if the shock doesn’t have a stem mount on each end, what does it have?
At least I know what’s wrong. Now to find the best solution I can afford! 🙂July 25, 2009 at 11:53 am #239319Larry MurphyParticipant
Hawk ,Glad you found out what is actually bottoming out . Sounds like shorter shocks would fix it if you are ok with the ride height and still have enough clearance before any other suspension parts bottom out if you replace the shocks with shorter ones. Your springs may be too weak or may have been cut too short by the previous builder. Stronger or taller springs would raise the car and may allow the present shocks to travel within their limits. Hope some one who has a CMC Chevette car can give you more info. CMC cars also used leaf springs which were cut in half .I think those used a Ford rear axle.July 25, 2009 at 6:03 pm #239320
O’Reilly’s had a Monroe 555001 shock what put my suspension pretty much in the middle of its 4 inch travel. Mounted them today and no more harsh bottoming out. Hurray!
One more item checked off the list. Only real question is whether I’ll outlive the todo list on this lil car. 🙂July 25, 2009 at 9:45 pm #239321Paul MossbergKeymaster
Only one option if you out-live the to-do list…get a second TD!
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)July 27, 2009 at 10:05 am #239322
I assumed you had the correct shocks on car when I mentioned that shocks will not cure “bottoming out”. I thought you were bottoming out on the suspension bump stops.
I used to have a link that listed all the Monroe shocks dimensions. It listed all the part numbers too. That way you could cross reference to another brand once you found the shock you needed.
Sounds like an older Ford or MOPAR shock on your car if it had studs on both ends.
Glad you found the solution. Happy Trails are ahead now!July 27, 2009 at 7:51 pm #239323Steve CritesParticipant
Glad to hear it was an easy fix. I checked my problem this weekend and found it was hitting the bump stops, not maxxing out the shocks. The shocks are fine, fairly new, and they are pretty much in the mid range with car at rest.
So I went old school and got coil spring boosters, (twist in aluminum “plugs”) from Mr. Gasket. In my younger days used way more than recommended to raise my dad’s Impala in front to give it a “gasser” look. (What an idiot!! )
Anyhow, 2 in each spring did not raise the body height at all and test drive says…….Fixed! No bump on the usual spots on the road. Can’t tell any change in handling, positive or negative. Wish I had gotten to this sooner, but you know how a to-do list goes.
RingoJuly 28, 2009 at 10:39 am #239324
Ringo, they still make those screw-in inserts!!!
I used to get mine free from the Tri-five Chevies in the local salvage yards…those were the days!
An MG-TD gasser…hmmmm?
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