I'm new to this forum, so I should probably do a short introduction.

I'm a full-time college student cursed with a love of British cars. This means I don't exactly have the funds to maintain a stock powertrain on an XJ6, but I adore the car's ride quality, legroom, cargo space, low center of gravity, weight distribution, rear wheel drive, and excellent cornering for its size and weight. Plus, it's classy as it gets, I mean come on...

Due to this I've been a deviant and put a stroked out Chevy small block (crate motor I got on the cheap) with a Buick 200-4R 4-speed overdrive automatic (out of a Grand National) into my XJ6. The original owner's engine took a chunk out of the side of the block . It's a little quicker than stock with 383 cubic inches (6.3L), and most importantly, it drops maintenance costs to the point that I can afford to keep it running as my daily and out of the junkyard on my shoestring budget.

Aside from the powertrain, the car is almost bone stock and has no outstanding issues.

On to the question at hand. My rear shocks are getting soft, so I need to swap them. I could just snag some generics, but I have a feeling you guys would know what the good stuff is, and I'd appreciate your suggestions. Despite the conversion, weight only changed in that the front end is roughly 50lbs lighter. I wouldn't think that would matter on such a massive car, but I don't have the experience that you guys have.

 

Boge is generally well liked for those wanted to keep the original characteristics. I like them

For a sporting flavor many like Spax and Bilstein, or the venerable Koni

Cheers
DD

 

Hello,
Welcome to our playpen!
(';')

 

Welcome, indeed.


Good folks here. Lots of knowledge and the willingness to share it.


I share the commonality. I worked and attended college in 48-52.
But, my steeds were far more mundane than a Jaguar "lump".
Employment at a "full service" station helped in many ways. Discounted gas and parts and acquisition of knowledge from the pro's.


Your car. A sophisticated IRS using "coil overs" for spring suspension and dampening. Four "shock", four springs.


Is the dampening function, "shocks" done for ?
1, With vigor, push the boot lid down, does the tail "bounce" or recover quickly. If it "bounces", it is time to shop for "shocks" aka Dampeners. If not. it is OK. Some reservation, but let's stick to shock/dampener issues.


2. OK, it bounces!!! Way back, a popular "coil over" company was Carrera. Atlanta, GA. based, I think. Do they still exist? I don't know.
Very helpful tech support. Give them spec's and they recommend combinations.


CAVEAT. The springs around the shocks are in a lot of tension. Changing them releases a lot of energy!! It must be done with skill and equipment or bad things will happen !!!


Carl

 

Sounds like a good running XJ. I've had four Buick Grand Nationals and only one had a uni bell case. Very rare case. The other three were BOP case. The trannies are easily identified with a rivet tag near the tail shaft with BRF labeled on them. I even rebuilt one myself while some of my Buick friends were saying I couldn't. I'm glad you posted because I need to replace mine also. I am going to email Ridetech about fitting their coil overs. Post some pics of your XJ, we'd love to see it

 

I've already tested the rear shocks with the 'bounce' test. They weren't rusting out, but they're not quite up to snuff. They're still functional, but they're getting soft so I'll want to swap them before they go out completely. Front end's shocks are still original and good so I'll be running them a little longer.

As for what kind of shocks, I'm a huge fan of the car's stock ride quality. However, I'm sure new advancements have improved the technology. Would swapping in some "sport" shocks like Doug recommended harm the ride quality any? I like fast cars don't get me wrong, but first and foremost an XJ6 is a cruiser. If it's comparable to stock ride quality, but simply offers better handling as opposed to mimicking the car's original characteristics then I'm all for it. If they sacrifice ride quality for performance handling, that would be an issue. If that's the case, I'd probably go with the Boge shocks.

As far as fitting the shocks, I don't really see any problems occurring. I'm lucky in that Dad's an automotive prototype engineer so I've got access to tools if I need them. Most of my car's work is done myself since he's always got projects going, but access to a lift makes things a LOT easier.

Thanks for the responses!

 

AFAIK Boge were British but I think are now owned by ZF of Germany.

 

I have had several 700R trans and the ratios of the 200R far exceeds the other choice... people just do not know that the closer 1-2 ratios and the better OD ratios is available..

 

I do not race ,..ralley.... maintain continuous high speeds through the mountain canyons ...etc... just everyday stuff,.. and I am happy with the KYB s I installed. Firm, not a harsh ride... Got them on my van and my collector car Buick Electra They are really nice on the Buick with the factory soft ride and a great highway cruiser. Have been really pleased with them on the Jag, but the Jag has been modified (16 inch wheels new suspension bushings etc.) So the ride has improved steering control accurate,.. tracks well on road seams

 

another option for the rears is to put together a set of height adjustable coilovers from QA1. Summit racing carries them and they many different sizes spring rates and all that. If you want some adjust ability then that might be something to look into

 

I ended up talking with the guys at Summit and they recommended Bilstein B6 shocks for a daily. I don't really car about maintaining the stock characteristics of the car, since it's already got a Chevy engine and practicality has to overrule everything else (except style points) for a daily. They're a newer design than the stock-style shocks from Monroe or KYB, so I'm hoping they maintain the same ride quality with superior road grip and durability, especially in poor weather.

Later on I'll want to do some suspension work to allow me to use the new ASD style shocks Monroe's got, but I don't want the car down for more than a few hours since I don't have any others. That'll have to come after I'm out of college and have a new daily.

When they come in, I'll take some pics and tell you guys what I think of them.

 

You are asking a lot from the shock absorbers!! All they can do is
dampen the movement of the suspension.


Bounce and jounce are the terms. Done with valves. The relations are adjusted. Quality means longer life.


Degree of wear is a lot. all wear out sooner or later....


A new cheap shock will perform better than a worn out high quality
unit.


In day to day, the function is limited. Stock suspensions are limited in the amount of travel. And for the most part the springs are on the soft side. Think low work load.


OTH, performance vehicles are in differing classes. A race buggy. Huge travel in the suspension. Lots of movement Lots of work load.
Big shocks, even remote resevoirs.


And, that doesn't even get to gas shocks.


Conclusion. Get the best deal available on a name brand. New for old will be felt in the seat of the pants....


That is if the old ones are worn??? If not....


Carl

 

Carl, I appreciate the advice, but I do understand how shock absorbers work. I made sure to test them before posting in the forum, and like I posted earlier, they failed the bounce test. Primarily I was just asking for brand recommendations. Quality and characteristics of shocks varies widely by brand and application, which I'm sure you're aware of. I'm not knowledgeable about the technical specifications of shocks, but their functional purpose, how they operate, and how to swap them is something I'm fully aware of.

I can see why you think I'm asking a lot of my shocks, but it's really not a lot to ask to get equivalent ride quality with a noticable improvement in handling when there's been over 30 years of shock absorber development since my car was built. The shocks weren't worn out when I got the car - I've been using it as my daily for 4 years now, so I know what they're like OEM. While they do fairly well, there's absolutely no reason they can't do better. New and old isn't really what I'm meaning to compare here, I mean to compare OEM with aftermarket.

Regardless, they're already on order so I'll post pics and my thoughts on them when I get them installed (hopefully) Friday.

 

So do you reuse the coils? I don't think I've looked at them up close to see if they can be disassembled. My car is a little lower in the rear. I'd like to get it level. I sent an email to ridetech or QA1 (can't remember which) but have not heard back.

 

383:


If you bought a quality "dampener", there will be a subjective improvement. The new or old thing, as simple as that.


You may or may not wish to research Bounce vs Jounce ratios. All done by valving. Example by exaggeration. Near stock car "optimized
for drag racing. Objective, rapid front to rear weight transfer. 0 or no up dampening. Nose rises rapidly.


Hafrod. Think struts in front suspensions. Only four instead of two to deal with. The coils are in tension around the dampers. They must be secured when taken apart. Same on reassembly. Lots of force in store....


Carl

 

Oh, Hafrod, I should be helping you!!! You are a pro, I a mere amateur.
Although at 87, today, I've messed with a lot of critters since I was 16!!


Carl

 

I'll send ya a plane ticket to come and help me Carl. I'll even cook you a steak. Although I'm not a pro, I'm not an amateur either. Think happy medium. Age has nothing to do with car building.

 

Thanks!!


But, I've enough on my plate here. Yard is way behind. My big old Bay lost two of it's trunks to the drought. lumber jack work to do.


I've my fill of airports from my past career. It is far worse now!!!
But, thanks.


Son brought a delicious Mexican food lunch yesterday. Daughter comes with steaks to grill later today.


And, as my house companion is my rescue dog, Coco, I don't go away for long or if the conditions are OK, he rides "shot gun". Unlike most dogs, he doesn't really like to ride, but goes as he likes to be near me.


Age sure does slow one down. But, what is the "hurry" !!!


You have a great project going on....


Carl

 

Well guys I've had a couple of long days, so while I do have pictures, I'll be posting them tomorrow instead of today.

Went home Friday and swapped the shocks. I just reused the stock coils, as they were free from rust and were still in good condition. I used a hydraulic press to drop out the retainers and remove the shocks. A couple of them were a little tricky, but some percussive maintenance with a concrete floor loosened them enough. Not exactly subtle, but it works and those coils are beefy enough that they couldn't care less about it. Then I just put the new shocks into the coils and put in the new retainers the reverse way I got them out. The tricky part was really the car's rear end itself. It's obvious that if the engineers at Jaguar tried a little bit harder, they could have made it more difficult to get your tools in. I used an air wrench and a couple of combinations to get it out, and it was a complete bear to do so. Also, you pretty much have to take off the rear wheels, or you can essentially give up on getting to the upper bolts for the coil/shock assembly. Add in the fact that the bolts strip very easily, and it's a fun time. I got it done with my father in under 2 hours, but we had a lift and it was still difficult. I'm lucky I had some extra rods for the lower coil/shock supports because one ended up stripped fairly badly.

As for the shocks themselves, I took them on about 8 hours worth of test driving out to Charleston, WV for a car meet with the West Virginia British Car Club. I'll post pictures of the cars there in another thread tomorrow, as I don't think it has much of a place in a thread about shock absorbers.

I noticed a difference in about 5 feet. First of all, there's the obvious benefits of having a rear suspension that actually functions properly. Aside from that, I remember very well how the car did before my shocks started going bad recently. The Bilsteins are in an entirely different league than the OEM shocks. First of all, the ride is definitely superior to the originals. I ran over a railroad track and my mother next to me didn't even notice. Minor potholes at 70+ mph showed no disruption to the ride. I definitely felt them a bit in the front, but the rear just soaked it up. As for the performance in the corners, it felt absolutely planted compared to OEM, and being someone that's been driving in snow for 4 years now, I look forward to the rear having some improved stability. With fully functional OEMs in the front and Bilsteins in the back, it's actually got better stability in the rear compared to the front. In hard cornering, it was the front that got floaty on me instead of the rear, which felt a bit unusual to be honest.

However, this isn't just a gleaming recommendation. I can definitely see how people would say that it changes the characteristics of the car. It doesn't feel the same in corners and it definitely behaves differently. As somebody that dailies, I felt that it was a noticeable and welcome improvement. However, I can see how those that love the original characteristics of the car may shy away from them. Performance and ride-quality wise though - 100% improvement. I would also say that while these shocks say 'performance', they really seem more focused on ride quality, with performance as a side benefit. Seeing as how that's exactly what I wanted from a new pair of shocks, I'm quite happy.